Evaporators Dr. M. Zahurul Haq Professor Department of Mechanical Engineering Bangladesh University of Engineering & Technology (BUET) Dhaka-1000, Bangladesh [email protected]http://teacher.buet.ac.bd/zahurul/ ME 415: Refrigeration & Building Mechanical Systems c Dr. M. Zahurul Haq (BUET) Evaporators ME 415 (2011) 1 / 12 Evaporators e266 c Dr. M. Zahurul Haq (BUET) Evaporators ME 415 (2011) 2 / 12 Classifications 1 Air Cooler: cools the air directly in a refrigerated space. Conditioned air is then distributed through air distribution systems. 2 Liquid Cooler: - chilled water is cooled to a lower temperature and is pumped to remote air handling units (AHUs), fan coil units (FCUs) or other terminals for air conditioning or other purposes. e267 e268 A liquid cooler is an evaporator, a component of a refrigeration system, whereas a chiller is a refrigeration package to produce chilled water. c Dr. M. Zahurul Haq (BUET) Evaporators ME 415 (2011) 3 / 12 Refrigerant Feed Methods in Evaporators 1 Dry/Direct Expansion (DX): amount of refrigerant feed into the evaporator is limited to that which can be completely evaporated by the time it reaches the end of the evaporator. 2 Flooded Refrigerant Feed: relies on natural convection to circulate more refrigerant through the evaporator than what evaporates. All inside surfaces of the evaporator are thus wetted with liquid refrigerant to enhance heat transfer. Vapour formed is separated in the surge drum and flows to the suction line. 3 Liquid Overfeed: liquid from either a mechanical pump or a gas-pressure pumping arrangement is supplied to the evaporators. c Dr. M. Zahurul Haq (BUET) Evaporators ME 415 (2011) 4 / 12
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Evaporators
Dr. M. Zahurul Haq
Professor
Department of Mechanical Engineering
Bangladesh University of Engineering & Technology (BUET)